The Greatest Floods in Earth's History
Between 15,000 and 13,000 years ago, a series of catastrophic floods swept across the Pacific Northwest. These weren't ordinary floods—they were among the largest floods ever documented on Earth.
What Happened?
A massive ice dam blocked the Clark Fork River in Montana, creating Glacial Lake Missoula. This lake held as much water as modern-day Lake Erie and Lake Ontario combined. When the ice dam periodically failed, the entire lake drained in just 48-72 hours.
The floodwaters traveled at speeds up to 65 miles per hour, carving out the dramatic landscape we see today.
Impact on Walla Walla
The floods deposited layers of sediment across the Walla Walla Valley, creating the complex soil profiles that make this region so special for wine growing. Geologists call these flood deposits Touchet beds — alternating layers of sand and silt that built up with each successive flood event. They're named for the Touchet River valley where they were first studied, but they underlie much of the Walla Walla Valley floor.
Today, valley floor vineyards sit on 2–4 feet of wind-blown loess over these Touchet bed layers. The floods didn't just reshape the landscape — they built the geological foundation that the valley's wine industry rests on. Combined with ancient volcanic basalt and wind-blown loess, these flood deposits create the layered soil profiles characteristic of the Columbia Basin's wine regions.
Wine Connection
The well-drained soils left by the floods force vine roots to dig deep for water, stressing the vines in a way that concentrates flavors in the grapes. This is why Walla Walla wines have such intensity and complexity.